When most of my clients open their MS Outlook 2007 Client, it will take 3-6 minutes for Outlook to actually open and I am wondering what occurs during the opening process.

I always see that Outlook is "updating folders", "updating calendars", and "updating mailboxes".

How can we improve the speed at which outlook opens and sends mail? We have 25% of our bandwidth reserved for smtp traffic on port 25, but I learned recently that outlook does not always use port 25 for sending mail.

If they are using RPC over HTTPS, I have seen where Outlook will attempt to RPC first, then when that fails it will "failover" to RPC over HTTPS, and that process can take a couple of minutes. How are they connected to Exchange?

That's what I was hinting at - what you can do is go into the Outlook Anywhere settings (Proxy) & click the "On fast networks, connect using HTTP first, then connect using TCP/IP" - I found that saved my field people about 1-4 minutes on boot up!